Implantable infusion pump

ABSTRACT

Implantable infusion pump having a casing, which receives a bellows receiving a propellant producing a vapour pressure and forming a space receiving a medicament and having a throttle means and a connection for a catheter, in which the space receives at least one resilient plastic bag containing the medicament and which is provided with a coupling piece to be attached to the throttle means.

The invention relates to an implantable infusion pump having thefeatures of the preamble of claim 1 and such as is e.g. known from DE 2604 113 C2. U.S. Pat. No. 4,820,273 discloses an infusion pump, in whicha membrane referred to as a bladder defines a medicament area withrespect to a pressure area.

The infusion pumps according to the preamble are implanted in patientshaving a constant need for a medicament supply, e.g. patients in painand spastics.

The known infusion pumps have a very complicated manufacture. The casingis regularly made from titanium, which is laser-welded for bringingabout a seal. The cleanness and sterility requirements with respect tothe casing interior are extremely high. Therefore the manufacture ofsuch infusion pumps is very expensive.

The problem of the invention is to provide an inexpensivelymanufacturable infusion pump.

According to the invention this problem is solved by the features ofclaim 1. The subclaims give advantageous developments of the invention.

The invention is described in greater detail hereinafter relative to thedrawings, wherein show:

FIG. 1 A plan view of such an infusion pump.

FIG. 2 A sectional view along line II--II of FIG. 1.

The infusion pump has a plastic casing 10, which receives a bellows 12,which in turn receives a propellant producing a vapour pressure. In therepresented embodiment, the remaining space 14 receives two resilientplastic bags 22, which in each case contain a medicament. The part ofthe space 14 not occupied by the bags 22 is filled with a liquid, e.g.glycerin, which does not attack the material of the bag and the casing.The liquid is chosen in such a way that it chemically binds thepropellant passing out of the bellows 14, so that it cannot penetratethrough the plastic casing into the body of the patient.

The casing 10 also carries a throttle means 16, to which is connected aconnection for a catheter 20.

The upper surface of the casing 10 directed towards the skin of thepatient after implanting the infusion pump is provided with a number ofrecesses 26 corresponding to the number of bags 22 to be received. Saidrecesses receive a plug 18 placed in the material of the plastic bag 22and penetratable by a needle. Through said first plug 18 the plasticbags 22 can be filled with the medicament to be administered to thepatient.

The plastic bags are also provided with a second plug 24 placed in thematerial thereof and which serves as a coupling piece towards thethrottle means 16.

The liquid producing a vapour pressure and received by the bellows 12exerts a pressure on the bags 22, said pressure being uniformlydistributed by the liquid surrounding said bags. On opening the throttlemeans a clearly defined quantity of the medicament consequently passesout of the bags 22 and into the catheter and consequently into the bodyof the patient.

In the case of the presently proposed infusion pump construction thecleanness and sterility requirements with respect to the casing interiorare far lower, because the medicament to be administered does not comeinto contact with the casing wall. In the preferred embodiment there isalso no need for an absolute sealing of the casing, because themedicament is received by the bag and when a leak occurs in the bellows,the propellant is bound by the liquid surrounding the bag.

I claim:
 1. Implantable infusion pump having a casing which receives abellows containing a propellant producing a vapor pressure, which casingforms a space and is provided with a throttle means and a connection fora catheter characterized in that the space receives at least two bagsmade from a resilient plastic and containing a medicament, provided witha coupling piece, and connected to the throttle means.
 2. Infusion pumpaccording to claim 1, characterized in that the casing is made fromplastic.
 3. Infusion pump according to claim 1, characterized in thatthe upper surface of the casing directed towards the skin of the patientfollowing implantation is provided with a number of recessescorresponding to the number of bags and which receive a plug penetrableby a needle.
 4. Infusion pump according to claim 1, characterized inthat the coupling piece is constructed as a plug placed in the materialof the plastic bag.
 5. Infusion pump according to claim 1, characterizedin that the part of the space not occupied by the bag is filled with aliquid.
 6. Infusion pump according to claim 1, characterized in that theliquid binds the propellant.